Information:
-General habitat
    Birds are found around the world and in every type of climate.  Tropical rain forests, savannas, and wetlands all have a high diversity of species.  Highly arid areas and high elevations have very few species of birds.  Many birds in North America and Europe will migrate south towards the equator in order to avoid colder winter climates.

 -Movement
    Birds are notorious for their ability to fly.  The unique physicality of bird feathers allows them to fly using many of the same physics that are used for airplanes.  Most birds can move their legs alternately to walk or run, and some species of bird are adapt at climbing trees.  The ostrich can run as fast as 40 mph.  Penguins posses the unique ability to "toboggan" on their stomachs across ice if they need to move quickly.  Many species of birds are excellent divers and swimmers, and the Emperor Penguin can dive up to 850 feet and stay submerged for up to 12 minutes.

-Feeding/Digestion
    Birds have a high metabolic rate and often feed on foods such as nectar, seeds, insects, rodents, fish, carrion, or other birds.  Most birds are diurnal, although some species, such as owls, are nocturnal or crepuscular (active during twilight hours).  Birds have a two chambered stomach consisting of the proventriculus, which secretes a highly potent acid, and a gizzard, which grinds and digest tough food.

-Circulation/Internal Transport
    Birds and mammals are the only animals with a four chambered heart.  The size of bird's hearts are proportionally larger than that of mammals or reptiles.  The circulatory system of birds is similar to that of most vertebrates.  Usually, the veins and arteries  lie next to each other. This way, the warm blood leaving the heart warms the cooler blood going to the heart; thus some heat is returned to the body core and conserved.  Countercurrent heat exchange and is typical of cold environment birds.

-Respiration
    Birds have the most efficient lungs of any animal.  They respire through a method of crosscurrent flow, or flow at a 90% angle.  It takes a bird two full breaths to cycle air through the body, with the air only flowing in one direction.  Birds are able to diffuse more oxygen into their than other animals.  Because they don't mix oxygen rich air and carbon dioxide rich air, the partial pressure of oxygen in a bird's lungs is the same as in the environment, allowing them to live more comfortably at higher altitudes.

-Nervous System
    The nervous system of birds is similar to that of mammals.  The central nervous system consists of the brain and spinal cord, and its job is to integrate sensory impulses from the environment, to stored learned information, and to coordinate voluntary and involuntary functions and movements.  Birds have a large optic lobe, a small olfactory lobe, and a highly developed cerebellum that is necessary to coordinate flight.

-Reproduction
    Birds lay eggs that, after hatching, are cared for in food and protection in varying levels depending on species.  Precocial birds can care for themselves independently within minutes of hatching; altricial hatchlings are helpless, when born and require extended parental care.  Nidifugous birds, such as partridges, are able to run immediately after hatching, as are most other ground-nesting birds.

-Excretion
    The kidneys in birds are twice the size of mammals, because of their active metabolism.  There are no urinary bladders in birds; instead, the urine mixes with the fecal matter in the cloaca to form a white paste.  As birds lay eggs and concentrated nitrogenous wastes would be fatal to the embryo, waste is stored in the insoluble form of uric acid.